Wellingborough's MP has called for "urgent action" to protect the Embankment horses, a week after two died in the field.
Peter Bone shared a photo of himself in front of the horses on Twitter and said: "Horses stranded in the flooded fields off the embankment.
"I have asked the RSPCA and DEFRA to take urgent action to protect the horses."
A spokesman for the RSPCA said: "We regularly monitor the horses in this area and have been out to check on them again because of the heavy rain which has flooded some of the fields.
"Although part of their field is flooded, the horses do have a dry area to stand on and plenty of hay to eat. We will continue to keep a close eye on them while the floods continue."
"We would urge anyone with horses and livestock to move their animals from areas at risk of floods and keep a close eye on water levels."
After Storm Ciara hit last weekend, a mare was found dead in the Irthlingborough Road field on Saturday and another mare had to be put down on Sunday by an emergency vet who was called by concerned members of the public.
Eve Williams, who was among those who tried to help the horse who had to be put down last weekend, has started a petition to help the horses.
It has had 9,206 signatures and is rising rapidly.
In the petition description, Eve describes the limits of the law and how open it is to interpretation. The petition is calling for the Animal Welfare Act to be changed.
Speaking today, an RSPCA spokesman said: "We’d like to thank animal lovers who continually monitor and raise concerns about horses being kept in this area around Wellingborough and would like to assure them work is taking place with other equine charities to safeguard their welfare.
"We understand and share the frustration about ongoing problems with horses in this area, which is made difficult to tackle when we cannot link individual horses with owners.
"We would like to trace the owner of the horses which were found in ill health last week and would urge anyone with information about who is responsible for them to contact the RSPCA appeals line on 0300 123 8018."